Field of the Invention
The present invention relates to a front suspension structure for a motorcycle or the like, in which a shock absorber and a front fork are separated.
Description of Background Art
As a motorcycle front suspension structure, a shock absorber is not assembled inside a front fork, but is arranged independently, as shown in FIG. 6. With this front suspension structure, a steering stem 101 is attached to a head pipe 100 so as to be capable of rotation, a top bridge 102 is provided on an upper end of the steering stem 101 while a bottom bridge 103 is provided on a lower end, a front fork 104 is supported by the top bridge 102 and the bottom bridge 103, the lower end of the front fork 104 and an axle 105 of the front wheel are linked by an axle support shaft 106, an upper end of a shock absorber 107 is attached to a cushion upper bracket 113 arranged on a lower end of the top bridge 102, a lower end of the shock absorber 107 is attached to a cushion arm 108 having one end pivoted at the bottom bridge 103, the cushion arm 108 and the axle support shaft 105 are linked by a push rod 109, and the vibration of the axle support shaft 105 is conveyed to the shock absorber 108 through the push rod 109 and the cushion arm 108.
It is possible to adjust the length of the push rod 109, making it possible to easily change the setting of the damping characteristics, and a lower end section of the push rod 109 has a two-legged section 110, as shown in FIG. 7, with a bearing section 111 of the axle support arm being fitted inside the two-legged section and joined from the side using a bolt 112.
A related structure is disclosed in Japanese Patent laid-open No. Hei. 6-47396, wherein a shock absorber is arranged between an axle support arm and a front fork without a push rod being provided. Vibrations of the axle support arm are conveyed to the shock absorber directly.
Regardless of the way in which the vibrations of the axle support shaft are conveyed to the shock absorber, the lower end of a shock absorber or push rod connecting to the axle support arm has a two-legged section 110, as described above. Therefore, if the axle support arm vibrates, the relationship between the two-legged section 110 and the axle support arm 105 is as shown in FIGS. 8(a)-(c).
Accordingly, in order to prevent interference between the two-legged section 110 and the axle support arm 105 it is necessary to make both sides 111a, 111a of sections that provide a bearing section 111 of the axle support arm in a hollowed out shape. In order to endow the axle support arm with the necessary rigidity for these conditions, the axle support arm must be made thick, which increases the weight.
In order to solve the above described problems, the present invention provides a front suspension structure for a motorcycle, having an axle support arm linking between a lower end of a front fork and a front wheel axle, with the rotation of the axle support arm being conveyed to a shock absorber either directly or through a push rod, wherein indented sections opening upwards are formed in the axle support arm, a lower end of the push rod or a lower end of the shock absorber is fitted into the indented section, and is rotatably linked to a shaft from a side direction via a bearing.
In this way, by making the shape of the axle support arm like an arc or a chevron, there is no need to consider avoiding interference between the axle support arm and the lower end of the pushrod or the lower end of the shock absorber, and the degree of freedom with regard to the shape is increased, making it possible to achieve the necessary rigidity without any accompanying increase in weight.
Also, by using a bolt as a shaft for rotatably supporting a lower end of the push rod or a lower end of the shock absorber, and positioning a head section of this bolt at a front wheel side, the bolt head section is not externally exposed, improving the external appearance.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.